Process for inhibiting corrosion in oil wells



Patented Oct. 21, 1952 UNlTE s'rA'rE PROCESS FOR INHIBITING CORROSION IN OIL WELLS U of Delaware No Drawing. Application April 3, 1950,

Serial No. 153,767

, Claims.

This invention relates to a method of inhibiting the corrosiveness to corrodible ferrous metal surfaces of corrosive fluids containing hydrogen sulfide. More particularly, the invention relates to means for inhibiting the corrosivity of sulride-containing, subsurface formation fluids to the corrodible conduits and attendant equipment through which the fluids are flowed and processed.

Crude oil containing soluble sulfides is often produced from subsurface formations and corrosion of conduits and attendant equipment is especially severe in those instances in which brine is produced along with the sour crude. Corrosive sulfide brines may include alkali metal sulfides, alkaline earth metal sulfides, acid sulfides such as hydrogen sulfide, and/or organic sulfides. Those brines containing hydrogen sulfide are especially corrosive to iron and steel equipment, the sulfides attacking the metal to form iron sulfide. Since these corrosive substances ocour in or are introduced into the fluids originating in the subsurface formations, corrosion may occur throughout the conduits and attendant equipment through which the fluids from the subsurface formations.v are flowed and produced. In other cases the corrosion may be more or less localized to a limited portion of the conduits through which the fluids from the subsurface formations are produced. In any case, corrosion of the conduits and/ or attendant equipment may be so severe as to require replacement of either or of both. Such replacements can be, and often are, extremely expensive. The expense involved is not limited merely to the cost of replacing the corroded equipment but may also involve killing the well in order to make repairs and to replace the corroded equipment. Not only-is the cost of killing the well high, but there is a marked loss in revenues due to having a well off production and to the necessity of having to' maintain additional wells and sources of supply to meet production requirements during the period when the well is off production for repairs as a result of the corrosion. Corrosion may, on occasion, be so severe as to result in failure of the equipment in which event the Well may flow wild. Enormous losses are incurred in such an eventuality.

The main object of the present invention is to provide a method of substantially eliminating or inhibiting the corrosive action of subsurface fluids containing sulfides to conduits and attendant equipment through which the fluids are produced from the subsurface formations in which they originate,

According to the present invention the corrosivity to corrodible ferrous metal surfaces by corrosive subsurface fluids including hydrogen sulfide is eliminated or substantially reduced by incorporating in the corrosive fluids a corrosion inhibiting amount of a fatty derivative of an alkyl or an alkanol amine. This fatty derivative is prepared by reacting a fatty material selected from the class of fatty oils and fatty acids and an alkyl or alkanol amine at a temperature in the. range of 300 to 550 F. in the presence of an alkaline reacting catalyst. Alkali metal hydroxides or carbonates, or mixtures thereof, may be suitably employed as an alkaline reacting catalyst.

Fatty acids which may suitably be used as the fatty material in the aforementioned. reaction include those fatty acids having at least 12 and no more than 26 carbon atoms per molecule. As examples of such acids, mention may be made of oleic, ricinoleic, linoleic, linolenic,

licanic, eleostearic, arachidonic, clupanodonic, lauric, myristic, arachidic, stearic, palmitic, etc.

- The fatty oils which maybe employed are those from which fatty acids having from l2.to 26 carbon atoms in the molecule can be derived. Fatty oils which have been found to produce especially efiective agents include tung oil, China-wood oil, oiticica, oil, chaulmoogra oil, cottonseed oil, menhaden oil, linseed oil, castor oil, and the like. It will be understood, of course, that mixtures of individual members of the aforementioned class of oils or mixtures of the individual members of the aforementioned class. of acids or mixtures including both oils and acids may be employed as the fatty material from which the corrosion inhibiting agent of the present invention is pro.-

duced. I

Various alkyl and/or alkanol amines may suitably be employed in the aforementioned reaction to produce the corrosion inhibiting reaction product of the present invention. Examples of alkanol amines which may be employed include triethanol amine, di-n-propanol amine, di-isopropanol amine, tri-n-propanol amine, triisopropanol amine, di-n-butanol amine, diisobutanol amine, di-tert. butanol amine, trin-butanol amine, tri-isobutanol amine, tri-tert. butanol amine, etc. Examples of alkyl amines which may be employed include triethyl amine, di-n-propyl amine, ,di-isopropyl amine, di-nbutyl amine, di-isobutyl amine, di-tert. butyl amine, tri-n-propyl amine, tri-isopropyl amine, tri-n-butyl amine, tri-isobutyl amine, tri-tert. butyl amine, tri-amyl amine (and its isomeric 3 forms), tri-hexyl amine (and its isomeric forms), etc. Rather than containing only alkanol or alkyl groups, the amines employed may contain both alkanol and alkyl groups. Examples of such alkyl-alkanol amines include di-ethyLethanol amine; ethyl,di-ethanol amine; ethyl,di-npropanol amine; di-ethyl,n-propanol amine; ethyl,di-isopropanol amine; di-ethyl,isopropanol amine; n-propyl,di-ethanol amine; isopropyl,diethanol amine; di-n-propyl,ethanol amine; diisopropyl,ethanol amine; ethyl,di-butanol amine; etc. While the amines employed preferably contain a total of between 6 and 18 carbon atoms in the alkyl and/or alkanol side chains, they may contain an even larger number of carbon atoms in the side chains. It will be understood, of course, that mixtures of the aforementioned amines may suitably be employed. Polymers of these amines, such as the polymers of tri-ethanol amine, may also be employed.

When the fattyderivatives of the present invention are prepared from a fatty oil, it is preferable that the fatty oil be present in the initial reaction mixture in a weight ratio of from about 1:1 to about :1 as compared to the alkyl or alkanol amine. When the fatty derivative. is prepared from a fatty acid, the fatty acid is preferably present in the initial reaction mixture in a weight ratio of from about 0.5:1 to about 3:1 ascompared to the amine.

The effectiveness as a corrosion inhibiting agent of the reaction product of fatty oils and/or fatty acids with alkyl amines and/ or alkanol amines depends upon the temperature at which the reaction is conducted. If the reaction is conducted at a temperature below about 300. F., the resulting reaction product possesses little, any, effectiveness as a corrosion inhibiting agent for well fluids containing hydrogen sulfide. On the other hand, if the reaction is conducted at a temperature in excess of about 550 F., the reaction product obtained tends to be of very high solidification point and of low solubility in the corrosive media. The particular temperature selected will depend to some extent upon the particular fatty oil or acid employed and upon the particular amine employed. For example, when the corrosion inhibiting agent is prepared from tri-ethanol amine and either tung oil, oiticica oil, chaul moogra oil, or cottonseed oil in the presence of sodium hydroxide, a reaction temperature maintained for 1 /2 to 4 hours in the range of 400 to 475 F. results in a product of especially desirable inhibition properties.

The extent of reaction, in addition to depending upon reaction temperature, also depends upon the time during which the reaction is permitted to continue. Ordinarily, an effective agent may be prepared when the reactants are reacted for a period of time in the range of from to 5 hours, although the preferred time is in the range of 1%; to 4 hours.

As hereinbefore mentioned, an alkaline reacting catalyst such asvalkali metal hydroxides or carbonates or mixtures thereof is employed. Examples of such materials are sodium hydroxide or sodium carbonate. The alkaline reacting catalyst concentrations ordinarily need not exceed about 3 per, cent by weight of the reactants although considerably lower concentrations may be successfully employed. For example, a concentration of 0.5 per cent by weight of sodium hy- I fact, as little as about 0.05 per cent of sodium hydroxide based upon the weight of the reactants has been found sufficient. Of course, mixtures of sodium hydroxide and sodium carbonate may be employed.

On completion of the reaction, the reaction product is allowed to cool and may be incorporated as such in the corrosive fluid to be treated or may be first dissolved in a suitable solvent such, for example, as an aromatic solvent or kerosene, and the solution incorporated in the corrosive fluid.

The amount of fatty derivatives of the present invention employed to inhibit the corrosion of ferrous metal surfaces by well fluid mixtures including moisture and hydrogen sulfide may be varied over a relatively wide range. However, it has been found that amounts within the range of 0.005 per cent to 0.1 per cent by volume of the fluid mixture give satisfactory results. Ordinarily,.an amount within the range of 0.005 per cent to 0.01 per cent by volume will be sufficient.

The following examples will illustrate the effectiveness of the corrosion inhibitors hereinbe-f fore described in inhibiting the corrosivity of a corrosive well fluid including hydrogen sulfide to corrodible ferrous metal surfaces.

EXAMPLE I 40 parts by weight of triethanol amine, 52 parts by weight of tung oil, and 2 parts by weight of sodium hydroxide were heated together at 445 to 465 F. for a period of about 5 hours. In order to test the effectiveness of the reaction product thus formed, 0.01 volume per cent and 0.005 volume per cent were added to two different samples of a 50:50 mixture of West Texas crude oil and West Texas brine, the mixture being saturated with hydrogen sulfide. Mild carbon steel coupons were immersed 31 times per minute for a period of 14 days in each of these samples. The extent of the corrosion inhibition obtained was compared with results obtained when similar coupons were exposed under identical conditions to a hydrogen sulfide saturated 50:50 mixture of West Texas crude oil and West Texas brine, no corrosion inhibitor being present. The comparative results obtained are shown in Table I below.

'60 grams of cottonseed oil, 38 grams of triethanol amine, and 0.5 gram of sodium hydroxide were heated together at a temperature of 410 to 443 F. for a period of more than 1 but less than 2 hours. In order to test the effectiveness of the reaction product thus formed, it was incorporated in a 50:50 mixture of West Texas crude oil and West Texas brine saturated with hydrogen sulfide, the concentration of the reaction product in the mixture being 0.01 volume per cent of the mixture. A mild carbon steel coupon was suspended in a sealedglass tube containing cc; of the oil-brine mixture and the coupon was imnersed in the mixture 31 times per minute for a period of 14 days- The extent of the corrosion inhibition obtained was compared with the results obtained when similar coupons were exposed under identical conditions to a hydrogen sulfide saturated 50:50 mixture of West Texas crude oil and salt water brine containing no inhibitor. The results obtained are shown in the following Table II belowz.

Table II Cfinbctoi Cfirrosidn .Rlgrccit Iniior ateo eucion' Iuhlbltor Vol. Per Coupons, Over cent n./ r. Blank- None 1 0.0232 Reaction Product of Cottonseed Oil, Triethanolamine, and Sodium Hydr0xide 0.01 I 0.0002 99 1 Average of seven determinations.

EXAMPLE III 60 grams of cottonseed oil, 38 grams of triethanol amine, 0.5 gram of sodium hydroxide,

and 2 grams of sodium carbonate were heated together at a temperature of 410 F. to 443 F. for a period of time greater than 1 hour but less than 2 hours. To test the effectiveness of this reaction product as a corrosion inhibitor, it was incorv porated in two different samples of a 50:50 mixture of West Texas crude oil and West Texas brine saturated with hydrogen sulfide. the concentration of the reaction product in the mixture being 0.005 and 0.01 volume per cent ofthe mixture, respectively. The extent of corrosion inhibition obtained was compared with the results obtained when similar coupons were exposed under identical conditions to a similar hydrogen sulfide saturated West Texas crude oil-West Texas brine mixture containing no inhibitor. The re- 1 Average of seven determinations.

EXAMPLE IV grams of tung oil, 30 grams of tri-amylamine, and 2 grams of sodium hydroxide were heated together at a temperature of 392 to 432 F. for a period of 2 hours. The resulting reaction product, when cooled, solidified ata temperature of 244 F. The effectiveness of this reaction product as an inhibitor was tested in a laboratory by using a concentration of 0.01, 0.005, and 0.001weight percent in a 50:50 mixture of West Texas crude oil and West Texas brine which was saturated with hydrogen sulfide. 100 cc. of the oil-brine mixture containing the aforementioned amounts of reaction product was placed in a glass tube and a mild carbon steel coupon was then suspended in the tube. The coupon was immersed in the brine-oil mixture 31 times per minute for a period of 14 days. The extent of the corrosion inhibition obtained was compared with the results obtained when similar coupons were exposed under identical conditions for a period of 4 hours.

to a hydrogensulfide saturated 50:50mixtureoi West Texas crude oil and West Texas brine,'this mixture containing no inhibitor. The results obtained are shown in Table IV below.

Table IV ICgILctoi Cfirrgsion RPgrcetnt niior, aeof euciou Inhlbttor Wt. Per- Coupons, Over cent In./Cr. Blank Ivorian 0.0344

Reaction Product oi'lung .Oil, 'Iriamylamine, and

Sodium Hydroxide 0.01 0.0015 96 Do 0.005 0.0111 68 0. 001 0.0306 11 EXAMP LE v P 47 grams of tung oil,- 47 grams of' triethanol amine, and 2 grams of sodium hydroxide were heated together at a temperature of 400-428 F. for a period of 3% hours. The reaction product obtained, when tested in lat-concentration of 0.01 volume per centofa 50:50 WestTexas crude oil- West Texas brine mixture .by the procedure out,- lined in Example II, reduced the corrosion-ofthe mixture by 95%.

EXAMP vI 58 grams of oiticica oil, 40 grams of triethanol amine, and 2 grams of sodium carbonate were heated together at a temperature of .385-403 F. The reaction product. when tested in aconcentration of 0.01 and 0.005 volume percent of a 50:50 West Texas crude oil- West Texas brine mixture in the mannerv outlined in Example II, reduced corrosion by 95%.

EXAMPLE VII 60 grams of chaulmoogra oil, 38 grams of triethanol amine, and 2 grams of sodium hydroxe ide were heated together at a temperature of- 426-438 F. for a period of 1 hour. This reaction product, when tested in a concentration of 0.01 volume percent of a 50.50 West'Texas crude oil-West Texas brine mixture'in the manner outlined in Example II, reduced corrosion by 9 5%.

EXAMPLE VIII 60' grams of menhaden oil, 39-grams of triethanol amine, 0.5 gram of sodium hydroxlda'and 2 grams of sodium carbonate were heated-together at a temperature of 404-438 F. for a period of 1% hours. The reaction product, when tested in a concentration of 0.01 volume percent of a 50:50 West Texas crude oil-West Texas brine mixture in the manner outlined in Example II,

reduced corrosion by 95%. I

EXAMPLE IX 7 ner outlined in Example II, reduced corrosion by 95%. (0.005 volume percent gave reduction.)

EXAMPLE X 1 hour, no catalyst being employed. This reac tion product, when tested in a concentration of 7 :01 volume percent of'a 50:50West Texas crude oil-West Texas brine mixture in the manner outlined in Example III, reduced corrosion by 95%. 0

sion by 95%.

EXAMPLE 2:11

A sample of tri-hydroxyethyl amine stearate obtained from a commercial source, when tested as an inhibitor for a 50:50 West Texas crude oil- West Texas brine mixture, gave a reduction in corrosion rate of This same commercial product, when heated at a temperature of 400 to440 F. for a period of approximately 1 hour,

reduced the corrosivity of the aforesaid brine-oil mixture by 95%. I

The nature and objects of the present invention having been fully described and illustrated, what is claimed as new and useful and is desired to be secured by Letters Patent is: 1. A method for reducing the corrosiveness to I corrodible ferrous metal of a corrosive petroliferous Well fluid including moisture and hydrogen sulfide which comprises introducing into said fluid a corrosion inhibiting amount of the reaction product of a fatty material selected from the group consisting of fatty acids having no less than 12 and no more than 26 carbon atoms per molecule and a fatty oil containing fatty acid radicals having no less than 12 and nomore than 26 carbon atoms with an amine selected from the group consisting of alkyl and alkanol amines havia a total of no less than 6 and no more than 18 carbonatoms per molecule, the reaction product being formed at a temperature in the range of '300 to 550v F. and in the presence of an alkaline reacting catalystselected from the group consisting of alkali metal hydroxide and alkali metal carbonate, the weight ratio of fatty material to amine being in the range of 0511.0 to about 2. A method for reducing the corrosiveness to corrodible-ferrous metal of a corrosive petroliferous well fluid including moisture and hydrogen ratio of tung oil to tri-ethanol amine being in the range of 1:1 to about 5:1.

3. A method for reducing the corrosiveness to corrodible ferrous metal of a corrosive petroliferous well fluid including moisture and hydrogen sulfide which comprises introducing into said "fluid a corrosion inhibiting amount of the reaction product formed by reacting tung oil with tri-amyl amine for a period of from to 5 hours at a temperature in the range of, 300 to 550 in the presence of an alkaline reacting catalyst selected from the group consisting of alkali metal hydroxide and alkali metal carbonate, the weight ratio of tung oil to tri-amyl amine being in-the range of 1:1 to about 5: 1-. I

4. A method for reducing the corrosiveness to corrodible ferrous metal of a corrosive petroliferous well fluid including moisture and hydrogen sulfide which comprises introducing into said fluid a corrosionginhibiting amount of the reaction product formed by reacting menhaden oil with triethanol amine fora period of from to 5 hoursat a temperature in the range of 300 to 550 F. in the presence of an alkaline reacting catalyst selected from the group consisting of alkali metal hydroxide and alkali metal carbonate, the weight ratio of menhaden oil to'tri-ethanol amine being in the range of 1:1 to about 5: 1.

5. A method in accordance with. claim 1' in which the reaction product is added to the corrosive well fluid in an amount in the range of 0.005 to 0.1% by volume of the fluid.

6. A method in accordance with claim 2 in which the reaction product is added to the corrosive well fluid inan amount in the range of 0.005% to 0.1% by volume of the fluid. I

'7. -A method in accordance with claim 3 in which the reaction product is added to the corrosive well fluid in an amount in the range of 0.005 to 0.1% by volume of the fluid.

8. A method in accordance with claim 4 in which the reaction product is added. to the corrosive well fluid in an amount in the range of 0.005% to 0.1%,by volume of the fluid. p 1

9.,A method for reducing the corrosiveness. to oorrodible ferrous metal of .a corrosive petroliferous well fluid including moisture and hydrogen sulfide which comprises introducing into ,said fluida corrosion inhibiting amount of the'reacjtion product formed by reacting cottonseed oil with triethanol amine for a period of from to 5 hours. at a temperature in the range of 300 to 550 F in the presence of an alkaline reacting catalyst selected from the group consisting of alkali metal hydroxide and alkali metal carbonate, the weight ratio of cottonseed oil to tri-ethanol amine being in the range of 1:1 to about 5:1.

10. A method in accordance with claim 9 in which the reaction product is added to the corrosive well fluid in an amount in the range of 0.005% to 0.1% by volume of the fluid.

MELBA L. LYTLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,992,689 Cox Feb. 26, 1935 2,366,013 Duncan Dec. 26, 1944 2,416,552 Valko Feb. 25, 1947 2,460,259 I Kahler Jan. 25, 1949 2,466,517 Blair Apr. 5, 1949 2,470,965 Woods May 25, 1949 OTHER REFERENCES Alkaterge, Bulletin, November 8, 1948, Commercial Solvents Corp. 

1. A METHOD FOR REDUCING THE CORROSIVENESS TO CORRODIBLE FERROUS METAL OF A CORROSIVE PETROLIFEROUS WELL FLUID INCLUDING MOISTURE AND HYDROGEN SULFIDE WHICH COMPRISES INTRODUCING INTO SAID FLUID A CORROSION INHIBITING AMOUNT OF THE REACTION PRODUCT OF A FATTY MATERIAL SELECTED FROM THE GROUP CONSISTING OF FATTY ACIDS HAVING NO LESS THAN 12 AND NO MORE THAN 26 CARBON ATOMS PER MOLECULE AND A FATTY OIL CONTAINING FATTY ACID RADICALS HAVING NO LESS THAN 12 AND MORE THAN 26 CARBON ATOMS WITH AN AMINE SELECTED FROM THE GROUP CONSISTING OF ALKYL AND ALKANOL AMINES HAVING A TOTAL OF NO LESS THAN 6 AND NO MORE THAN 18 CARBON ATOMS PER MOLECULE, THE REACTION PRODUCT BEING FORMED AT A TEMPERATURE IN THE RANGE OF 300* TO 550* F. AND IN THE PRESENCE OF AN ALKALINE REACTING CATALYST SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL HYDROXIDE AND ALKALI METAL CARBONATE, THE WEIGHT OF RATIO OF FATTY MATERIAL TO AMINE BEING IN THE RANGE OF 0.5:1.0 TO ABOUT 5.0:1.0. 